The effects of granulocyte-macrophage colony-stimulating factor on tumour-infiltrating lymphocytes from renal cell carcinoma

Fusion cytokine IL-2-GMCSF enhances anticancer immune responses through promoting cell-cell interactions

Background

Potent antitumor responses can be induced through cytokine immunotherapy. Interleukin (IL)-2 and granulocyte–macrophage colony-stimulating factor (GM-CSF) are among the most effective cytokines to induce tumor-specific systemic immune responses and can act synergistically. To overcome the limitations of combined use of these two cytokines, we have constructed an IL2-GMCSF fusion protein and characterized its antitumor effects in this study.

Methods

The expression of IL-2 receptor and GM-CSF receptor of cell lines were detected with quantitative real-time PCR. On this basis, the bioactivities of IL2-GMCSF, especially effects on DC2.4 cells were assayed. Another function of IL2-GMCSF—bridge two types of cells—was assessed by cell contact counting and cytotoxicity assays. The anti-tumor activity in vivo of IL2-GMCSF was evaluated in the melanoma model. The statistical significance among treatment groups were determined by One-Way ANOVA.

Results

The fusion protein IL2-GMCSF maintained the activities of IL-2 and GM-CSF, and could significantly promote DC2.4 cell activities, including phagocytosis, proliferation and cytokine secretion. In addition to the inherent cytokine activity, IL2-GMCSF bridges direct cell–cell interactions and enhances splenocyte killing efficacy against multiple tumor cell lines in vitro. Co-injection of IL2-GMCSF and inactivated B16F10 mouse melanoma cells induced complete immunoprotective responses in about 30 % of mice.

Conclusion

These results suggested that IL2-GMCSF can efficiently regulate immune responses against tumors. Furthermore, as the bridging effect relies on both IL-2R and GM-CSFR and promotes interactions between immune and tumor cells, IL2-GMCSF may be utilized as a useful tool for dissecting specific immune responses for future clinical applications.

Aldesleukin in advanced renal cell carcinoma

Renal cell carcinoma accounts for 2-3% of all malignancies. The most common subtype [85%] is the clear cell variant. A total of 30% of patients present with metastatic disease at diagnosis and another 30-40% will develop metastases during the course of the disease. Conventional cancer treatment is not effective, but cytokines including recombinant interleukin-2 (aldesleukin) have demonstrated clinical activity of various degrees. This drug profile provides a review of the literature on studies using aldesleukin in patients with metastatic renal cell carcinoma. Aldesleukin has been used in different dose schedules applying various administration routes, as either monotherapy or in combination with other cytokines, chemotherapy, endocrine treatment and adoptive cellular immunotherapy. Although a large number of randomized trials have been performed with different treatment strategies, it still remains uncertain whether the dose or combination of aldesleukin with other agents substantially influence treatment outcome. It appears that factors other than those that are treatment related are responsible for the course of the disease.

Granulocyte-macrophage colony-stimulating factor and interleukin-2 fusion cDNA for cancer gene immunotherapy

Genetic engineering of tumor cells to express both granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-2 can induce synergistic immune antitumor effects. Paradoxically, the combination has also been reported to down-regulate certain immune functions, highlighting the unpredictability of dual cytokine use. We hypothesized that a GM-CSF and IL-2 fusion transgene (GIFT) could circumvent such limitations yet preserve synergistic features. We designed a fusion cDNA of murine GM-CSF and IL-2. Protein structure computer modeling of GIFT protein predicted for intact ligand binding domains for both cytokines. B16 mouse melanoma cells were gene modified to express GIFT (B16GIFT), and these cells were unable to form tumors in C57bl/6 mice. Irradiated B16GIFT whole-cell tumor vaccine could also induce absolute protective immunity against challenge by live B16 cells. In mice with established melanoma, B16GIFT therapeutic cellular vaccine significantly improved tumor-free survival when compared with B16 expressing both IL-2 and GM-CSF. We show that GIFT induced a significantly greater tumor site recruitment of macrophages than combined GM-CSF and IL-2 and that macrophage recruitment arises from novel chemotactic feature of GIFT. In contrast to suppression by GM-CSF of natural killer (NK) cell recruitment despite coexpression of IL-2, GIFT leads to significant functional NK cell infiltration as confirmed in NK-defective beige mice. In conclusion, we demonstrated that a fusion between GM-CSF and IL-2 can invoke greater antitumor effect than both cytokines in combination, and novel immunobiological properties can arise from such chimeric constructs.

Immune effects of escalating doses of granulocyte-macrophage colony-stimulating factor added to a fixed, low-dose, inpatient interleukin-2 regimen: a randomized phase I trial in patients with metastatic melanoma and renal cell carcinoma

Previous studies in cancer patients demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) upregulated the interleukin (IL)-2 receptor on T lymphocytes and monocytes suggesting that subsequently administered IL-2 would produce greater immune effects. The authors treated 21 patients with metastatic renal cell carcinoma and melanoma on a randomized phase I study to test this hypothesis. All 21 patients received a fixed dose of IL-2 (72,000 IU/kg every 8 hours for 5 days) administered intravenously as an inpatient. Patients were randomized to receive IL-2 alone or in combination with GM-CSF at a dose of 125 or 250 mcg/m /d (Sargramostim; Immunex Corporation, WA, U.S.A.) daily for 7 days by subcutaneous injection starting on day 1, the day before IL-2 treatment. The results from this study demonstrated that GM-CSF did not worsen the toxicities produced by IL-2 alone. Grade 3 confusion occurred in four patients, three who received IL-2 alone. No partial or complete tumor responses were seen. Assays of serum soluble IL-2 receptor (sIL2R) and neopterin, measures of T cell and monocyte activation, respectively, demonstrated a significant increase in sIL2R but not neopterin, 24 hours after the first dose of GM-CSF. In combination with IL-2, the higher dose of GM-CSF (250 mcg/m ) produced higher sIL2R levels on days 3 and 7 than the 125-mcg/m dose of GM-CSF or IL-2 alone. Although neopterin levels did not increase after 1 day of GM-CSF, the addition of IL-2 resulted in a significantly increased neopterin level on day 3 at the higher dose of GM-CSF. On day 7, neopterin levels in all three groups were similarly increased over baseline. Ten days after treatment, neopterin levels had returned to normal, but sIL2R levels remained markedly increased (12 fold) over baseline in the higher GM-CSF dose group. The authors conclude that 1) monocyte activation was not significantly enhanced by 1 day of GM-CSF treatment; 2) the 250-mcg/m GM-CSF dose plus IL-2 produced superior T cell activation compared with a lower dose of GM-CSF plus IL-2 or to IL-2 alone; and 3) the combination of GM-CSF and IL-2 was safe and tolerable but was not associated with any clinical responses.

Interferon Alpha, GM-CSF-Activated T Cells, and IL-6 in Renal Cell Carcinoma

Treatment of renal cell carcinoma (RCC) has historically involved surgical removal of the primary tumor when localized, but when presented with metastatic disease the options have been limited. Approximately 30% of patients present with metastatic disease implicating a generally poor prognosis. The most significant advances have occurred in the area of immunotherapy as treatment for metastatic disease. This is because RCC is generally resistant to chemotherapy and radiation. One of the major successes of immunotherapy has been with interleukin-2 (IL-2). Initial IL-2 therapy proved difficult due to the significant administrative and side effect problems that occurred. This led to numerous variations in dose scheduling and delivery to identify an optimal beneficial way of administering IL-2. In addition, investigation also led to other immunotherapy agents such as interferon and cellular therapy.

Sensitization of immunoresistant prostate carcinoma cell lines to Fas/Fas ligand-mediated killing by cytotoxic lymphocytes: independence of de novo protein synthesis

BACKGROUND

We recently reported that drug-resistant prostate tumor cells (DU145, PC-3) are resistant to Fas-mediated killing by cytotoxic lymphocytes, and that this resistance can be overcome by treatment with subtoxic concentrations of chemotherapeutic drugs. Fas belongs to the tumor necrosis factor (TNF) family of receptors. Since resistance to TNF-alpha-mediated killing has been shown to be due, in part, to the presence of protective factors and that inhibitors of protein synthesis can sensitize cells to TNF-alpha killing, we hypothesized that resistance to Fas-mediated killing may be due to similar mechanisms. Since sensitization is achieved with chemotherapeutic drugs, and some chemotherapeutic drugs can also inhibit protein synthesis, we tested whether sensitization of prostate tumor cells to Fas ligand (Fas-L) occurred through inhibition of protein synthesis in a manner analogous to that of TNF-alpha.

METHODS

The effect of chemotherapeutic drugs on protein synthesis in DU145 and PC-3 cells was characterized by (3)H-leucine incorporation assays. We also determined the ability of inhibitors of protein synthesis and chemotherapeutic drugs to sensitize Fas and TNF-resistant DU145 cells to killing. The ability of RNA (actinomycin-D, Act-D) and protein synthesis inhibitors (cyclohexamide (CHX), emetine) to block drug-mediated sensitization to Fas-L killing was analyzed. Sensitivity to Fas-L killing was determined by the (51)Cr-release assay using human lymphokine-activated killer cells (LAK) and tumor-infiltrating lymphocyte (TIL) effector cells and the murine Fas-L-expressing PMMI cells.

RESULTS

The drugs cis-diamminedichloroplatinum (II) (CDDP), adriamycin (ADR), and etoposide (VP-16) sensitized DU145 and PC-3 cells to Fas killing. CDDP and ADR, which sensitized DU145 and PC-3 cells to Fas-L- and TNF-mediated killing, inhibited de novo protein synthesis in both cell lines, while VP-16 only inhibited protein synthesis in DU145 cells. Further, neither CHX nor emetine sensitized DU145 or PC-3 cells to Fas-L-mediated killing, despite blocking >90% de novo protein synthesis. In contrast, CDDP, VP-16, and the protein synthesis inhibitors, Act-D and CHX sensitized DU145 cells to TNF-alpha killing. Finally, pretreating cells with protein synthesis inhibitors (CHX, emetine) did not abrogate drug-mediated sensitization to Fas-mediated killing.

CONCLUSIONS

These findings demonstrate that downregulation of protective factors by protein synthesis inhibition may not be the primary mechanism of drug-mediated sensitization to Fas-L killing in prostate cell lines. These findings also suggest that drug-mediated sensitization to Fas-L killing may be due to modifications of preexisting gene products that participate in Fas-L-mediated apoptosis.

Effect of intraperitoneally administered recombinant murine granulocyte-macrophage colony-stimulating factor (rmGM-CSF) on the cytotoxic potential of murine peritoneal cells

We studied the effect of recombinant murine granulocyte-macrophage colony-stimulating factor (rmGM-CSF) on the cytotoxic potential of murine peritoneal cells. Mice received rmGM-CSF intraperitoneally using different dosages and injection schemes. At different time points after the last injection, mice were sacrificed, peritoneal cells isolated and their tumour cytotoxicity was determined by a cytotoxicity assay using syngeneic [methyl-3H]thymidine-labelled colon carcinoma cells. Also, the cytotoxic response to a subsequent in vitro stimulation with lipopolysaccharide was determined. Upon daily injection of 6000-54,000 U rmGM-CSF over a 6-day period, the number of peritoneal cells increased over ten fold with the highest rmGM-CSF dose. Increases in cell numbers was mainly due to increases in macrophage numbers. Upon injection of three doses of 3000 U rmGM-CSF per day for 3 consecutive days, the number of macrophages remained elevated for minimally 6 days. Although the peritoneal cells from rmGM-CSF-treated mice were not activated to a tumoricidal state, they could be activated to high levels of cytotoxicity with an additional in vitro stimulation of lipopolysaccharide. Resident cells isolated from control mice could be activated only to low levels of tumour cytotoxicity with lipopolysaccharide. Tumour cytotoxicity strongly correlated with nitric oxide secretion. When inhibiting nitric oxide synthase, tumour cell lysis decreased. Thus, the expanded peritoneal cell population induced by multiple injections of rmGM-CSF has a strong tumour cytotoxic potential and might provide a favourable condition for immunotherapeutic treatment of peritoneal neoplasms.

Granulocyte-macrophage--colony stimulating factor in metastatic renal cell carcinoma: a phase II trial

BACKGROUND

Due to lack of success with standard chemotherapy and only modest success with immunotherapy, metastatic renal cell carcinoma (RCC) is associated with a poor prognosis. Granulocyte-macrophage-colony stimulating factor (GM-CSF) is a cytokine with potential antitumor activity, including stimulation of tumor necrosis factor (TNF) and interleukin-1 secretion. It is also a potent growth factor for and activator of antigen-presenting dendritic cells. GM-CSF toxicity may be mediated by TNF, and inhibition of TNF release by pentoxifylline (PTX) may ameliorate these toxic effects. The authors conducted a Phase II trial to determine the activity of GM-CSF in metastatic RCC and to study the effect of PTX on GM-CSF toxicity.

METHODS

Twenty-four eligible patients with metastatic RCC received 10 microg/kg of GM-CSF per day, administered subcutaneously, on a 14-days-on/14-days-off schedule. Twelve patients received concurrent PTX at a dose of 400 mg administered orally 4 times per day.

RESULTS

One patient experienced prolonged stability of disease after having progressive disease on entry. Two other patients experienced substantial slowing of their progressive disease while on study. One of these patients had rapidly progressing metastases on other immunotherapy before receiving GM-CSF. Toxicity was not diminished in patients treated with PTX; it included hyperleukocytosis, nausea, vomiting, pain, fever, skin reactions, myalgia, and fatigue.

CONCLUSIONS

GM-CSF at the dose and schedule described in this report has minor activity against metastatic RCC, and PTX does not ameliorate its side effects.

Immunosensitization of prostate carcinoma cell lines for lymphocytes (CTL, TIL, LAK)-mediated apoptosis via the Fas-Fas-ligand pathway of cytotoxicity

Several reports suggest that immunotherapy mediated by cytotoxic lymphocytes is beneficial in the destruction of drug-resistant tumor cells. Cytotoxic T lymphocytes kill target cells by two main mechanisms, namely by the perforin pathway and by the Fas-ligand (Fas-L) pathway. The role of the Fas-L pathway in tumor cell killing is not clear because many Fas(+)-expressing tumor cells are resistant to the Fas-L agonist cytotoxic anti-Fas antibody. The human prostate tumor cell lines (PC-3, DU145, and LnCAP) express Fas on the cell surface but are resistant to killing by anti-Fas antibody. This study examined the sensitivity of prostate tumor cells to Fas-L-mediated cytotoxicity and sensitization of the tumor cells by drugs to Fas-L-mediated killing. All three prostate tumor cell lines are resistant to Fas-L killing as determined by the use of the murine CTL hybridoma PMMI that kills only through the Fas-L pathway. However, the addition of subtoxic concentrations of CDDP or VP-16 significantly sensitized the PC-3 and DU145, but not LnCAP, tumor cells to Fas-L killing and apoptosis by PMMI. The sensitization of tumor cells by drugs was inhibited by neutralizing anti-Fas antibody. These findings demonstrate that immunoresistant Fas(+)-expressing DU145 and PC-3 prostate tumor cells can be sensitized by drugs to Fas-L killing. We then examined the role of Fas-L killing by TIL and LAK cells. All three prostate tumor cell lines were sensitive to killing by TIL and LAK and cell killing was primarily mediated through the Ca(2+)-dependent perforin pathway because it was blocked by the addition of EGTA/MgCl2. Sensitization by CDDP or VP-16 did not significantly augment killing of untreated tumor cells by TIL or LAK cells. However, in the presence of EGTA/MgCl2, the addition of CDDP or VP-16 significantly augmented killing of PC-3 and DU145, but not LnCAP, by TIL and LAK, and killing was blocked by neutralizing anti-Fas antibody. These findings demonstrate that both TIL and LAK exhibit a Fas-L-mediated killing pathway that is revealed once the perforin pathway is blocked by the Ca2+ chelator EGTA/MgCl2. Altogether, these findings show that drug-resistant, Fas(+)-expressing PC-3 and DU145 prostate tumor cells can be sensitized by CDDP and VP-16 to killing by Fas-L-bearing CTL, TIL, and LAK cells. Sensitization of tumor cells by drugs may augment the efficacy of immunotherapy in the eradication of tumor cells that are resistant to Fas-L-mediated killing.

Granulocyte-macrophage colony-stimulating factor improves immunological parameters in patients with refractory solid tumours receiving second-line chemotherapy: correlation with clinical responses

In this report, we studied the immunorestorative properties of subcutaneously administered granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients with refractory solid tumours receiving second-line chemotherapy. Such patients exhibit abnormal immune responses in vivo and in vitro and, therefore, it was of interest to examine the effect of GM-CSF-induced immunomodulation on clinical response. We examined patients with primary malignant carcinomas (head and neck, n = 10; urogenital tract, n = 17; penis n = 6; colorectal, n = 8) who were treated with carboplatin (JM8), 300 ng/m2 on days 1 and 22, leucovorin (LV), 200 mg/m2 plus 5-fluoracil (5-FU), 500 mg/m2 on days 8, 15 and 29 and four cycles of daily injections with placebo or GM-CSF, 300 micrograms/day on days 3-6, 10-13, 17-20 and 24-27. Peripheral blood was collected from the patients one day after the end of each of the four-cycle injections with placebo or GM-CSF, namely on days 7, 14, 21 and 28. Peripheral blood mononuclear cells (PBMC) were tested in the autologous mixed lymphocyte reaction (AMLR) and for natural killer (NK) or lymphokine-activated killer (LAK) cell activity. Cytokine levels in serum were measured by immunoenzymatic (ELISA) assay. A total of 21 patients received a four-cycle regimen with GM-CSF (Group 1) and 20 were similarly treated with placebo (Group 2). All received standard chemotherapy as outlined above. Before GM-CSF treatment, all patients exhibited increased serum levels of interleukin-1 (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), IL-6 and prostaglandin E2 (PGE2) and decreased serum levels of IL-2. Cellular immune responses (AMLR, NK- and LAK-cytotoxicity) were also low in all patients. Five patients from Group 1 had a PR (partial response), 2 patients had CR (complete response), and 14 patients had stable disease. Seven patients from Group 2 showed progressive disease, 3 had a PR and 10 had stable disease. All immune parameters were significantly improved during treatment in Group 1 but remained unchanged or even deteriorated in Group 2. Administration of GM-CSF during treatment of cancer patients with conventional chemotherapeutic drugs results in a marked potentiation of deficient cellular immune responses in vitro and a change towards normalisation of cytokine serum levels. The results reported herein support the use of GM-CSF as immunopotentiator during chemotherapy, but more patients must be studied before definite conclusions can be drawn.

Potentiation of antitumor CTL response by GM-CSF involves a B7-dependent mechanism

We have previously demonstrated the importance of endogenous GM-CSF production for the B7-2-dependent potentiating effect of exogenous TNF for CTL generation by stimulation cultures of splenic cells from mice bearing a large MOPC-315 tumor. Here we show that addition of GM-CSF to stimulation cultures of such tumor-bearer splenic cells also leads to the generation of enhanced anti-MOPC-315 CTL activity via a B7-dependent mechanism. However, while the potentiating effect of TNF was previously shown to be IL-2-independent, the potentiating effect of GM-CSF is shown here to be completely IL-2-dependent. Still, the potentiating activity of exogenous GM-CSF for the in vitro generation of CTL activity is shown to depend completely on endogenous TNF production. Finally, TNF and GM-CSF may cooperate in enhancing the in vivo generation of CTL activity in MOPC-315 tumor bearers because low-dose melphalan (L-phenylalanine mustard) therapy, which was previously shown to lead to the rapid up-regulation of TNF production at the tumor site and the subsequent TNF-dependent in vivo acquisition of potent CTL activity, is shown here to lead to the rapid up-regulation of GM-CSF production at the tumor site.

The in vitro effects of interleukin-12 upon tumor-infiltrating lymphocytes derived from renal cell carcinoma

Clinical trials utilising interleukin (IL)-2 with tumor-infiltrating lymphocytes (TIL) have demonstrated efficacy in the treatment of metastatic renal cell carcinoma (RCC). Several cytokines, as well as growth factors have demonstrated modulatory effects upon the biological properties of TIL from RCC, suggesting a potentially important role for cytokines other than IL-2 in the development of active and tumor-specific TIL. IL-12 was recently characterized as a natural-killer-cell-stimulatory factor or cytotoxic-T-cell-maturation factor. These properties of IL-12 prompted us to investigate the impact of this cytokine upon the activation of TIL from human RCC. In an attempt to enhance the in vitro growth and activity of renal TIL, we have grown eight renal TIL cultures in varying concentrations of IL-2 (8, 40, 80, 400 U/ml) and IL-12 (200 U/ml). In addition, IL-12 (200 U/ml) was added to TIL cultures pre-activated with IL-2 (400 U/ml). Growth, cell expansion, and the ability of TIL to release certain cytokines upon tumor stimulation were determined. Proliferation assays, phenotypic analysis, and cytotoxicity assays were performed at an early and a late culture stage. IL-12, alone and when added to suboptimal concentrations of IL-2, failed to induce TIL growth. While the addition of IL-12 to optimal doses of IL-2 suppressed TIL culture expansion, sequential culture exposure first to IL-2 and then to IL-2+IL-12 increased the number of cells expressing CD3+/CD56+ and these cultures demonstrated enhanced in vitro lysis of autologous tumor. IL-12 clearly demonstrated a sequence-dependent impact of the biological behaviour of TIL from RCC. The optimal use of IL-12 in the in vitro expansion of renal TIL may result in cells with an enhanced specific anti-tumor effect.